Microbial pathogens produce proteins that can be recognized by the adaptive immune response in an infected host. Identification of these immune targets is a prerequisite for the rational design of novel vaccines and better diagnostics, including those directed against the category B bioterrorism agent Salmonella. The specific aims of this proposal are: Aim 1. Use an established high throughput screening technology to identify common aspects of the Salmonella proteome recognized by antibodies induced by Salmonella infection. Aim 2. Identify and confirm antigenic targets of Salmonella-specific CD4 T cells from among the targets of isotype-switched antibody responses. Aim 3. To generate a prototype sub-unit typhoid vaccine that is immunogenic and protective in highly susceptible mouse strains. Our preliminary data demonstrate that high throughput screening of microbial proteomes is an effective strategy for the identification of microbial proteins targeted by the adaptive immune response. Our hypothesis is that identification and production of natural antigenic targets of Salmonella-specific responses will allow the development of improved diagnostics and a sub-unit vaccine for typhoid fever, a disease that kills over 600,000 people per year and is a significant bioterrorism threat to the US. The elderly and very young are most at risk from typhoid, yet currently available live attenuated vaccines are not licensed for use in these populations. There is an urgent need to develop an effective sub-unit vaccine that could be specifically targeted to the most vulnerable demographics. Our hypothesis will be tested using novel high-throughput proteome technology to identify Salmonella protein targets of the adaptive immune system and develop a prototype sub-unit vaccine for typhoid. PUBLIC HEALTH RELEVANCE: Typhoid is an infectious disease that kills over 600,000 people per year in developing countries and has been recognized as a potential bioterrorist threat in the US. This proposal aims to identify the major antigenic targets recognized by antibodies and T cells from infected mice and humans, and use this information to generate a novel sub-unit vaccine. This proposal therefore has the potential to uncover target antigens that may be important in the development of novel vaccines and diagnostics for typhoid fever.